She opened this discussion with several definitions. First, she provided the National Institute of Health’s definition of health disparities, which are “differences in the incidence, prevalence, mortality, and burden of diseases and other adverse health conditions that exist among specific population groups in the United States.” She followed by defining healthcare disparities as differences in access to or availability of facilities and services. She then defined health status disparities as the variation in rates of disease occurrence and disabilities between socioeconomic and/or geographically defined population groups. Social determinants of health are conditions in the environments in which people live, learn, work, play, worship, and age that impact health, functioning, and quality of life. Patterns of social engagement, a sense of security, and a sense of well-being are all impacted by where people live. Some specific examples Dr. Ford provided as social determinants of health include racial residential segregation, which results in many minorities living in neighborhoods far from grocery stores and medical facilities, living in multi-generational households that make it difficult to protect those in the household that are frail or sick. Racial/ethnic minorities are also over-represented in detention centers and jails, which are associated with unique risks from living in close proximity to others and other factors.
Dr. Ford then described the definition of obesity as a body mass index of over 25. From CDC data, there is a high age-adjusted prevalence of obesity (in this case BMI > 30) in the United States. This is very slightly more common in men versus women, with the exception of non-Hispanic black women relative to non-Hispanic black men (56.9% versus 49.6%). Geographically, rates of obesity vary by self-reported race and state within the United States.
Obesity (due to reduced physical activity, higher-calorie/saturated fat/reduced fruit and vegetable intake) may increase the risk of cancer via increased hormonal or oxidative stress or inflammatory mediators. Cancers that are associated with obesity include meningioma, thyroid, esophageal adenocarcinoma, multiple myeloma, breast, liver, gallbladder, upper stomach, kidney, pancreas, endometrial, colorectal, and ovarian.
To highlight the social determinants of health as related to obesity and cancer risk, Dr. Ford focused on her state of South Carolina (SC), especially the I-95 corridor. Over 35% of residents self-report as obese, representing the 12th-highest obesity rate in the USA. The poverty rate for Black residents in South Carolina is 150% higher than the rate for White residents. Many counties in SC have a persistent child and total population poverty, and these tend to be counties that have a higher percentage of minority populations living in them with higher rates of poverty. These same counties also tend to have higher rates of cancer deaths, including from breast and prostate cancer. In South Carolina, black men have the highest incidence of all cancers, and the highest all-cancer 5-year age-adjusted mortality.
Dr. Ford and colleagues have come up with several models to illustrate the social determinants of health disparities.
Social-environmental factors like poor housing, low levels of education, low-wage jobs that may not cover health insurance, and not having access to high-quality nutritional food together make people more susceptible to disease and have limited access to healthcare, resulting in health disparities.
In a more complicated model, Dr. Ford and colleagues relate structural life inequalities with chronic stress that leads to behaviors that promote physical and psychiatric health disparities.
In their most complicated model, Dr. Ford and colleagues relate environmental factors with a predisposition to stressors, poor health behaviors, and physical health disorders that promote pathophysiology that adversely affect health.
Future work being pursued by Dr. Ford includes investigating the stronger association between obesity and cancer in some racial/ethnic groups and how obesity may exert different biological effects in different populations.
Presented by: Marvella Elizabeth Ford, PhD, Professor in the Department of Public Health Sciences and Associate Director of Population Sciences and Cancer Disparities, Hollings Cancer Center, Medical University of South Carolina, Columbia, South Carolina
Written by: Alok Tewari, MD, PhD, Medical Oncologist at the Dana-Farber Cancer Institute, at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting, Virtual Annual Meeting #ASCO21, June, 4-8, 2021